Previously, when compiled in developer mode, a call into libsystemd with
invalid parameters would result in an abort. This means that it's effectively
impossible to install such libsystemd in a normal system, since various
third-party programs may now abort. A shared library should generally never
abort or exit the calling program.
In python-systemd, the test suite calls into libsystemd, to check if the proper
return values are received and propagated through the Python wrappers.
Obviously with libsystemd compiled from git, the test suite now fails
in a nasty way.
So rework the code to set assert_return_is_critical similarly to how we handle
mempool enablement: the function that returns true is declared as a week
symbol, and we "opt in" by linking a file that provides the function in
libsystemd-shared. Effectively, libsystemd and libudev always have
assert_return_is_critical==false, and our binaries and modules enable it
conditionally.
Let's not leak details from src/shared and src/libsystemd into
src/basic, even though you can't actually do anything useful with
just forward declarations from src/shared.
The sd-forward.h header is put in src/libsystemd/sd-common as we
don't have a directory for shared internal headers for libsystemd
yet.
Let's also rename forward.h to basic-forward.h to keep things
self-explanatory.
Now that the necessary functions from log.h have been moved to macro.h,
we can stop including log.h in macro.h. This requires modifying source
files all over the tree to include log.h instead.
Various functions in log.h are only used by asserts, and there's
enough assertion related stuff in macro.h to justify a separate header
which also makes it easier to avoid circular dependencies.
Let's introduce assert-util.h and an accompanying fundamental header
and move all the assertion related stuff over there. PROJECT_FILE is
moved over to macro.h.
Several test cases intentionally trigger assert_return(). So, to avoid
the entire test fails, this introduces several macros that tentatively
make assert_return() not critical.
The man page says nothing about "e". Glibc clearly accepts it without fuss, but
it is meaningless for a memory object (and probably doesn't work). This use is
not portable, so let's avoid it.
The compiler may decide computations like these are not doing anything
and decide to optimize them away. This would defeat the whole fuzzing
exercise. This macro will force the compiler to materialize the value
no matter what. It should be less prone to accidents compared to using
log functions, which would either slow things down or still optimize the
value away (or simply move it into the if branch the log macros create).
The benefit over assert_se would be that no requirement is made on the
value itself. If we are fine getting a string of any size (including
zero), an assert_se would either create a noisy compiler warning about
conditions that would alawys be met or yet again optimize the whole
thing away.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
The fuzzers will be used by oss-fuzz to automatically and
continuously fuzz systemd.
This commit includes the build tooling necessary to build fuzz
targets, and a fuzzer for the DNS packet parser.
Zbigniew Jędrzejewski-Szmek
Daan De Meyer
Yu Watanabe
Frantisek Sumsal
Jan Janssen
Evgeny Vereshchagin
Lennart Poettering
Jonathan Rudenberg